System and method for transmitting random access data using orthogonal frequency division multiple access

ABSTRACT

Disclosed is a random access data transmission system and method using OFDMA. The system includes a scheduling ID into an access grant on a preamble for a random access, and transmits it together with an acknowledgment or a non-acknowledgment of the preamble, a base station uses the scheduling ID to notify the mobile station of a random access data transmittable time and a data transmission channel through a control channel, and the mobile station transmits a preamble in advance. After receiving a transmission assignment instruction corresponding to a scheduling ID through the control channel, the mobile station transmits random access data through an assigned channel.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent Reissue applicationSer. No. 13/422,300, filed on Mar. 16, 2012, of U.S. Pat. No. 7,680,156issued on Mar. 16, 2010, which claims the benefit under 35 U.S.C. §365of International Application PCT/KR2004/002279, filed Sep. 8, 2004,which designated the United States and was published in English, whichclaims priority to Korean Patent Application No. 10-2003-0090149, filedon Dec. 11, 2003. These applications, in its entirety, are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a system and method for transmittingrandom access data using OFDMA (orthogonal frequency division multipleaccess.) More specifically, the present invention relates to a systemand method for transmitting random access data using OFDMA for allowinga plurality of mobile stations to transmit burst-characterized datathrough an uplink common channel for the purpose of effective usage ofresources.

(b) Description of the Related Art

A wireless mobile communication system divides a total resource such asfrequency bands or data rates into many smaller ones, schedules themaccording to respective users' requests, and thus shares the resource byusing multiple access methods such as time division, frequency division,and code division.

The method for a plurality of mobile stations to transmit intermittentdata through an uplink common channel for the purpose of effective usageof resources is a random access method for allowing all the mobilestations to have transmission rights and transmit data randomly.

One of the random access methods is to allow a mobile station totransmit a preamble to a base station in advance. The preamble isgenerated by using a randomly selected code from among distinguishablecodes. After having received a corresponding access grant on thepreamble from the base station, the mobile station transmit the actualrandom access data.

The above-noted method for transmitting random access data allows thepreamble and the data to be transmitted through a common random accesschannel, and additionally requires resource assignment.

Further, one of methods for responding to the preamble transmitted fromthe mobile station is to use the code which is received when an accessgrant signal is generated, and re-transmit the preamble. Another one isto use code and channel information which is captured at the time ofreceiving the preamble.

Since a lesser amount of resources is needed for transmitting thepreamble, it is allowable to assign a lesser amount of resourcesirrespective of a random access request by the mobile station. However,it is inefficient to assign the transmission resource for transmissionof random access data irrespective of a random access request by themobile station.

SUMMARY OF THE INVENTION

It is an advantage of the present invention to transmit ACK/NACKinformation including a scheduling ID when a base station responds to apreamble of a random access mobile station.

It is another advantage of the present invention to provide a system andmethod for transmitting random access data using OFDMA for allowing abase station to assign a specific ID to each preamble when receiving thepreamble, variably assign a channel for transmitting random access dataaccording to resource assigned conditions, and notify a mobile stationof assignment of the channel resource by using ID.

In one aspect of the present invention, provided is a random access datatransmission system using OFDMA between a mobile station and a basestation, wherein the mobile station comprises: a resource selector forrandomly is selecting a preamble transmission channel and a code; apreamble transmitter for generating a preamble based on the transmissionresource information selected by the resource selector and transmittingthe preamble to the base station through a preamble transmissionchannel; a preamble access grant processor for receiving and processingacknowledgment or non-acknowledgment information including a schedulingID contained in the preamble access grant from the base station; and adata transmitter for transmitting random access data through a datatransmission channel assigned to the mobile station based on theinformation processed by the preamble access grant processor.

In another aspect of the present invention, provided is a random accessdata transmission system using OFDMA (orthogonal frequency divisionmultiple access) between a mobile station and a base station wherein thebase station comprises: a preamble receiving processor for receiving apreamble from the mobile station and extracting corresponding preambleinformation; an ID manager for assigning a specific scheduling ID toeach mobile station and managing the specific scheduling ID so that themobile station may use a assigned data transmit channel; a scheduler forscheduling a data transmission time, and a transmission quantity of themobile station with the scheduling ID assigned to the mobile station bythe ID manager according to channel environments and requirements of themobile stations; an access grant processor for determining anacknowledgment/non-acknowledgment status based on the preambleinformation of the preamble receiving processor and the is scheduling IDof the ID manager, and transmitting preamble access grant configuringinformation including the scheduling ID to the mobile station; and adata receiving processor for receiving the random access data through aassigned data transmission channel from the mobile station according toa transmission result of the access grant processor, and processingthem.

The ID manager recovers the scheduling ID assigned to the mobile stationwhen the data receiving processor finishes receiving of transmittedrandom access data.

In still another aspect of the present invention, provided is a randomaccess data transmission method using OFDMA between a mobile station anda base station, wherein the procedure of mobile station comprises: (a)selecting a preamble transmission channel and a transmission radioresource related to a code used for transmitting a preamble for a randomaccess to the base station; (b) generating a preamble and transmittingthe preamble to the base station using the transmission radio resourceselected in (a); (c) receiving preamble access grant configuringinformation including a scheduling ID andacknowledgment/non-acknowledgment information assigned by the basestation with respect to the preamble transmitted in (b), and checking asuccess or failure in transmission of the preamble, and the schedulingID; and (d) allowing the mobile station to check an assignment of thedata transmission channel by using the mobile station's scheduling IDincluded in a control channel according to a checking result in (c), andtransmitting random access data to the base station through the datatransmission channel assigned to the mobile station.

In step (d), the mobile station uses extracted transmission controlinformation related to timing, a frequency, and power from the accessgrant information received in (c) to transmit random access data.

In still yet another aspect of the present invention, provided is arandom access data transmission method using OFDMA between a mobilestation and a base station, wherein the procedure of base stationcomprises: (a) allowing the base station to receive and analyze apreamble transmitted from the mobile station, and assigning a specificscheduling ID when the mobile station can be scheduled; (b) determiningan acknowledgment or a non-acknowledgment and forming preamble accessgrant configuring information according to the preamble informationanalyzed in (a) and an assigned status of the scheduling ID, andtransmitting the preamble access grant configuring information to themobile station; (c) allowing the base station to schedule a datatransmission time, a transmission channel, and a transmission quantityof each mobile station according to the mobile stations' channelenvironments and requirements, and notifying the mobile station ofscheduled results by using scheduling ID; and (d) receiving randomaccess data from the mobile station corresponding to the scheduling IDdetermined in (c) through the data transmission channel, and processingthe random access data.

The step (d) comprises recovering the scheduling ID assigned to themobile station when the reception of the random access data transmittedfrom the mobile station is finished.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate an embodiment of the invention,and, together with the description, serve to explain the principles ofthe invention:

FIG. 1 shows a configuration diagram of a random access datatransmission system using OFDMA according to a preferred embodiment ofthe present invention;

FIG. 2 shows a configuration of an uplink frame according to a preferredembodiment of the present invention;

FIG. 3 shows a configuration of a downlink frame according to apreferred embodiment of the present invention; and

FIG. 4 shows a data transmission process of the random access datatransmission method using OFDMA according to a preferred embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, only the preferred embodiment ofthe invention has been shown and described, simply by way ofillustration of the best mode contemplated by the inventor(s) ofcarrying out the invention. As will be realized, the invention iscapable of modification in various obvious respects, all withoutdeparting from the invention. Accordingly, the drawings and descriptionare to be regarded as illustrative in nature, and not restrictive. Toclarify the present invention, parts which are not described in thespecification are omitted.

A random access data transmission system using OFDMA according to thepreferred embodiment of the present invention will be described indetail with reference to FIG. 1.

FIG. 1 shows a configuration diagram of a random access datatransmission system using OFDMA according to a preferred embodiment ofthe present invention, FIG. 2 shows a configuration of an uplink frameaccording to a preferred embodiment of the present invention, and FIG. 3shows a configuration of a downlink frame according to a preferredembodiment of the present invention.

As shown in FIG. 1, when using the random access method including thecase in which a mobile station registers to a cell for the first time,the case in which the mobile station requests a state transition, andthe case in which the mobile station requests a handover from one cellto another, the random access data transmission system using OFDMAassigns a scheduling ID included in downlink access grant transmitted bythe base station 200 to the uplink preamble transmitted by the mobilestation 100 so that the mobile station may transmit the random accessdata to the base station 200 through a data transmission channelassigned to the scheduling ID.

For this purpose, the mobile station 100 comprises a resource selector110, a preamble transmitter 120, a preamble access grant receivingprocessor 130, and a data transmitter.

The resource selector 110 selects transmission radio resources likecodes, preamble transmission channel for transmitting the preamble for ais random access to the base station codes.

The preamble transmitter 120 generates a preamble by using informationon the transmission radio resource selected by the resource selector110, and transmits the corresponding preamble to the base stationthrough the preamble transmission channel.

In the OFDMA/FDD system which uses different frequency bands for uplinksand downlinks, the preamble transmitter 120 fixes a specific slot in anuplink frame for an available time of preamble transmission. An uplinkframe is made up a plurality of slots. Radio frequency resources of thespecific slot are divided into a plurality of sub-channels. The preambletransmitter 120 transmits the preamble which is generated by using thecode which is distinguishable from among the different codes through thesubchannel randomly selected from among the subchannels.

In this instance, slots of the uplink frame except the slot which isfixed for transmitting the preamble are divided into control informationtransmission channels and data transmission channels, and the randomaccess data are loaded on part of the data transmission channel andtransmitted to the base station 200.

As shown in FIG. 2, the uplink frame having a predetermined length ofT_(frame) comprises a plurality of slots where the length of the slotsis T_(slot), excluding the final slot having a length of T_(slot′).

The possibility of each slot's transmission of the random accesspreamble is determined according to the position of the slot in theframe. When the preamble transmission position is defined to be thefinal slot within the is frame, the final slot of the frame is fixed tothe time for transmitting the preamble, and the radio resources of theslots are divided into subchannels and are then used.

The mobile station 100 randomly selects one of the radio resources whichare divided as the subchannels at the time of transmitting the preamble,uses the code which is distinguishable by different codes, and transmitsthe generated preamble to the base station 200.

The slots except the final slot are divided into control informationtransmission channels and data transmission channels. A channel fortransmitting the random access data is not classified as a separatetransmission channel, and the random access data are transmitted byusing part of the data transmission channels.

The preamble access grant receiving processor 130 receives a preambleaccess grant including a scheduling ID and ACK/NACK information on thepreamble from the base station 200 according to the transmission by thepreamble transmitter 120, and processes them.

The data transmitter 140 transmits the random access data to the basestation 200 through the data transmission channel of the scheduling IDassigned to the mobile station 100 based on the information processed bythe preamble access grant receiving processor 130.

The base station 200 comprises a preamble receiving processor 210, an IDmanager 220, a scheduler 230, an access grant processor 240, and a datareceiving processor 250.

The preamble receiving processor 210 receives preambles from the isrespective mobile stations 100, and extracts preamble informationincluding codes, timing, and power through the preambles.

The ID manager 220 assigns a specific scheduling ID to each mobilestation 100 and manages it so that the mobile station 100 may use a datatransmission channel specified by the base station 200, and alsorecovers and manages the scheduling ID assigned to the mobile stationwhen the data receiving processor 250 finishes receiving of transmittedrandom access data.

The scheduler 230 assigns the resources of the packet service, and indetail, it considers requirements including a channel environment andQoS of the mobile stations, and determines transmission times andquantities of the mobile stations to which the scheduling IDs are givenaccording to a scheduling algorithm.

The access grant processor 240 loads preamble access grant informationin a specific slot of the downlink frame including a plurality of slots,and transmits the same to the mobile station 100.

As shown in FIG. 3, the downlink frame includes a plurality of slotshaving a constant length T_(frame), and it has the same length as thatof the uplink frame.

The slots of the downlink frame comprises a slot T_(slot′)forsynchronization and cell search, and downlink traffic slots T_(slot)which include a transmission time of data traffic and a transmissiontime of control signal traffic.

The period of physical channels for transmitting the control signaltraffic can be a multiple of the frame period, which represents that thedata configured by block units are partially divided and transmitted foreach slot.

The data transmitted to the downlink through the channel at thetransmission time of the control signal traffic include broadcastinginformation, paging information, state management information, and datatransmission control information.

Since control signal information channels for transmitting the controlsignal information divide and use the orthogonal frequencies because ofcharacteristics of the OFDMA system, a preamble access grant channel fortransmitting access grants on the preamble transmission can beconfigured with N subchannels from among the channel.

It is required to use the restricted radio resources with an appropriateratio and purpose, and the assignment ratio of the resources is variedaccording to the cell configuration in the OFDMA system.

Therefore, it is desirable for the base station to separately notify themobile station of configuration information of a preamble access grantchannel, use the configuration information of the preamble access grantchannel, and allow the mobile station to check the preambleacknowledgements ACK/NACK so that the base station may effectivelymanage the channel for transmitting the access grant of the preamble,compared to the method for fixing part of the control signal informationchannel to be a preamble access grant channel in consideration of themaximum value of the random access request available in the existingcell.

The data receiving processor 250 receives and processes the randomaccess data transmitted by the mobile station 100 which has received theaccess grant of the access grant processor 240.

An operation of the random access data transmission system using OFDMAaccording to a preferred embodiment will now be described with referenceto a drawing.

FIG. 4 shows a data transmission process of the random access datatransmission method using OFDMA according to the preferred embodiment ofthe present invention.

As shown in the random access data transmission method using OFDMA, theresource selector 110 of the mobile station 100 initially selects atransmission radio resource used for transmitting the preamble in stepS1.

The preamble transmitter 120 receives information on the transmissionradio resource selected by the resource selector 110, generates apreamble, and transmits it to the base station 200 through a preambletransmission channel in step S2.

The preamble receiving processor 210 of the base station 200 analyzesthe preamble received through the preamble transmitter 120, extractspreamble information including codes, timing, and power, and the IDmanager 220 assigns a scheduling ID to the mobile station to bescheduled in step S3.

The access grant processor 240 determinesacknowledgment/non-acknowledgment status on the preamble provided fromthe mobile station according to the preamble information extracted fromthe preamble receiving processor 210 and assigned status of thescheduling ID provided by the ID manager 220.

The access grant processor 240 configures preamble access grantconfiguring information by using the scheduling ID information, ACK/NACKinformation, and preamble information extracted from the preamble, andtransmits the preamble access grant configuring information which isaccess grant information to the mobile station 100 through the controlinformation transmission channel specified by the base station 200 instep S4.

The preamble access grant receiving processor 130 of the mobile station100 receives the preamble access grant configuring information from theaccess grant processor 240 through the preamble acknowledgement channel,and checks successful preamble transmission status and the scheduling IDin step S5.

When finishing transmission of the preamble access grant configuringinformation, the base station 200 transmits assignment information ofthe data transmission channel determined after scheduling together withthe scheduling ID assigned to a random access mobile station 100 by thescheduler 230 to the mobile station 100 through the control informationtransmission channel in steps S6 and S7.

The random access mobile station 100 checks assigned status of the datatransmission channel of the scheduling ID transmitted through thecontrol channel in step S8, and transmits the random access data throughthe data transmission channel assigned to the mobile station 100 in stepS9.

In this instance, the mobile station 100 minimizes the influence givento the data transmitted to the base station by another mobile station byusing transmission control information including timing, a frequency,and a power received through the preamble access grant configuringinformation, and transmits the random access data through the datatransmission channel.

When the base station 200 finishes receiving the random access datathrough the data receiving processor 250, the ID manager 220 recoversand manages the scheduling ID assigned to the corresponding mobilestation in step S10.

As described, the base station 200 assigns data transmission channelsfor variably transmitting the random access data according to assignedresource status to the access grant of the preamble transmitted from themobile station.

To achieve this, the base station 200 provides a specific scheduling IDfor each preamble when transmitting an access grant on the preamblereceived from the mobile station to the downlink, and notifies themobile station of assignment information on the data transmissionchannel determined through the scheduling ID.

It is desirable to use the scheduling ID as an identifier of the mobilestation used by the scheduler 230 and use the same for the physicallayer and the MAC layer.

In consideration of the channel condition and QoS of each mobilestation, the scheduler 230 selects a mobile station to which the datatransmission channel will be assigned, and transmits correspondingassignment information through the data transmission control channel,and hence, the mobile station checks the assignment information in thedata transmission control channel through the scheduling ID assigned tothe mobile station, and transmits the random access data through thedata transmission channel.

In this instance, the data transmission channel is a channel forallowing is the mobile station which is registered to the base stationand is in the active state to transmit the data.

After receiving the random access data from the mobile station, the basestation 200 transmits them to the system through a path other than thatof the data of the registered mobile station. Therefore, the OFDMA-basedrandom access data transmission system and method according to thepreferred embodiment improves conventional inefficient usage of thetransmission resources through assigning a separate random access datatransmission channel.

While this invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not limited to thedisclosed embodiments, but, on the contrary, is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims.

As described in the OFDMA-based random access data transmission systemand method, the base station loads the mobile station's transmissioncontrol information and the scheduling ID information into the accessgrant of the preamble received from the mobile station and transmitsthem so that the mobile station may transmit the random access datathrough the data transmission channel without an additional separatedchannel, thereby enabling effective usage of the radio resources, andtransmitting the data without influencing data transmission of othermobile stations by using the transmission control information.

1.-15. (canceled)
 16. A random access method in a wireless communicationsystem, the method at a mobile station comprising: transmitting apreamble, without random access message, through preamble transmissionchannel to a base station; receiving a preamble response message thatconveys a scheduling ID and an assignment information of radio resourceof data transmission channel for random access data transmission; andtransmitting random access data to the base station through the radioresource of data transmission channel assigned to the mobile station,wherein the scheduling ID is specific for the mobile station andidentification for random access procedure, wherein the preamble isgenerated by using a code that is distinguishable from other codes,wherein the random access data is transmitted after the preamble istransmitted and the preamble response message is received in response tothe preamble, and wherein the scheduling ID is used for a physical layerand a Medium Access Control (MAC) layer of the mobile station.
 17. Themethod of claim 16, wherein the assignment information of radio resourceis associated with the scheduling ID.
 18. The method of claim 16,wherein the preamble response message conveys timing and powerinformation for transmitting random access data.
 19. (canceled)
 20. Themethod of claim 16, wherein data transmission channel over which randomaccess data is transmitted is different from preamble transmissionchannel over which the preamble is transmitted.
 21. The method of claim16, wherein a configuration for receiving the preamble response messageis determined in consideration of the maximum value of random accessrequests available in the base station, and the preamble responsemessage is received from the base station with reference to theconfiguration.
 22. A random access method in a wireless communicationsystem, the method at a base station comprising: receiving a preamble,without random access message, through preamble transmission channelfrom a mobile station; transmitting a preamble response message thatconveys a scheduling ID and an assignment information of radio resourceof data transmission channel for random access data transmission; andreceiving random access data from the mobile station through the radioresource of data transmission channel assigned to the mobile station,wherein the scheduling ID is specific for the mobile station andidentification for random access procedure, wherein the preamble isgenerated by using a code that is distinguishable from other codes,wherein the random access data is transmitted after the preamble istransmitted and the preamble response message is received in response tothe preamble, and wherein the scheduling ID is used for a physical layerand a Medium Access Control (MAC) layer of the mobile station.
 23. Themethod of claim 22, wherein the assignment information of radio resourceis associated with the scheduling ID.
 24. The method of claim 22,wherein the preamble response message conveys timing and powerinformation for receiving random access data.
 25. (canceled)
 26. Themethod of claim 22, wherein data transmission channel over which randomaccess data is received is different from preamble transmission channelover which the preamble is received.
 27. The method of claim 22, whereina configuration for transmitting the preamble response message isdetermined in consideration of the maximum value of random accessrequests available in the base station, and the preamble responsemessage is transmitted to the mobile station with reference to theconfiguration.